1. Technical Field
The present invention relates generally to circuitry for driving signals onto a communication line. More particularly, the present invention relates to reducing electromagnetic interference (EMI) in such signal transmission.
2. Description of Related Art
As electronic and computer technology continues to evolve, communication of data among different devices, either situated nearby or at a distance, becomes increasingly important. It is also increasingly desirable to provide such data communications at very high speeds, especially in view of the large amount of data required for data communications in intensive data consuming systems using graphical or video information, multiple input-output channels, local area networks, and the like. Hence, it is now more desirable than ever to provide for high speed data communications among different chips on a circuit board, different circuit boards in a system, and different systems with each other.
A problem of increasing significance for such data communications is substantial electromagnetic interference (EMI) radiation, often exceeding acceptable levels. As the number of data lines and the rate of data driving and transmission increases, the EMI emitted increases correspondingly.
An early prior art method of reducing EMI radiation involves physical shielding. Physical shielding may reduce EMI radiation, but physical shielding may be cumbersome and costly, and may not be effective enough to sufficiently reduce EMI radiation depending on the frequencies involved.